SMTP Error 354 is a typical problem reported by email senders. Understanding this error and why it occurs is critical for effective troubleshooting.
This error takes many forms, disturbing email campaigns. Imagine writing a crucial email only to be prevented by a cryptic error message.
In this article, we discuss the complexities of SMTP Error 354.
What is SMTP Error 354?
SMTP Error 354 typically appears with a brief message or explanation. For example: Error 354: Start mail input; end with <CRLF>.<CRLF>
This error message signifies that the server is ready to accept the email content but requires proper termination with “<CRLF>.<CRLF>” (carriage return, line feed, period, carriage return, line feed).
Depending on the email client or application being used, the error message may vary slightly in format and wording, but the essence remains consistent. There is a specific issue encountered during email transmission.
Network connectivity issues: Poor internet connection or network disturbances might impede communication between email client and SMTP server, resulting in Error 354.
Firewall or Antivirus blocking SMTP traffic: Overly restrictive firewall or antivirus settings can block outgoing SMTP traffic and prohibit successful email transmission.
Incorrect SMTP server settings: Misconfigured SMTP server settings mean incorrect server address, port number, or login credentials.
Oversized email attachments: Sending emails with large attachments that exceed size limits specified by the SMTP server or email providers can esult in SMTP Error 354.
Server overload or resource constraints: The error may occur due to server overload, resource constraints, or temporary issues with the SMTP server’s capacity to handle incoming emails especially during peak usage times.
- Adjusting SMTP server settings:
- Access Gmail account settings and ensure SMTP server details (server address, port, encryption method) are correctly configured.
- Checking network connection:
- Verify that your device is connected to a stable internet connection to ensure uninterrupted communication with Gmail’s SMTP server.
- Verifying firewall or antivirus Settings:
- Temporarily disable firewall or antivirus software to check if they are blocking SMTP traffic. If so, adjust settings to allow outgoing email communication.
- Updating SMTP port settings:
- Navigate to Outlook account settings and ensure that the correct SMTP port (usually 587 or 465) is configured.
- Ensuring server authentication:
- Confirm that SMTP server authentication settings are enabled and correct authentication credentials are provided.
- Testing email sending on alternate networks:
- Try sending the email from a different network to determine if the issue is specific to your current network setup.
- Clearing outbound email queue:
- Check for any stuck emails in the Outbox and remove them. Sometimes, pending emails can cause SMTP errors.
- Authenticating SMTP server credentials:
- Ensure that the SMTP server credentials (username and password) configured in Yahoo Mail settings are accurate.
- Reviewing email attachment size limits:
- Confirm that the size of email attachments complies with Yahoo’s attachment size limits to avoid triggering SMTP errors.
Incomplete message error:
- This variation occurs when the email message is not properly terminated with “<CRLF>.<CRLF>”, as required by the SMTP protocol. It indicates that the email content was not successfully transmitted to the SMTP server.
Connection timeout error:
- Error 354 can occur if the connection between the email client and the SMTP server times out before the email transmission is completed. This could be due to a network issue or a server outage.
Authentication failure:
- If the SMTP server rejects the email transmission owing to invalid or illegal authentication credentials, Error 354 with an authentication failure message may appear.
Attachment size limit exceeded:
- Sending emails with attachments larger than the SMTP server’s permitted size limit can result in Error 354. This variation indicates that the email was rejected due to large attachments.
Server capacity reached:
- During periods of heavy server demand or resource limits, the SMTP server may fail to handle inbound emails, resulting in Error 354. This variation indicates that the server’s capacity has been reached, and email transmission is momentarily suspended.
Warmy.io is an essential tool for optimizing email deliverability and resolution of errors like SMTP Error 354. Here’s how:
- Warmy.io helps evaluate your emails’ deliverability by checking on sender reputation, content of the email, and behavior of the recipient.
- The AI-powered email warmup solution gradually builds trust with ISPs, ensuring that senders are recognized as legitimate. It does this by mimicking natural email interactions to show ISPs that your emails are trusted and valuable
- It identifies potential deliverability issues that could cause SMTP errors.
- Warmy.io checks various email blacklists with our email deliverability test to see if your domain or IP address is listed, allowing you to take prompt action to de-list and improve email deliverability.
- Warmy also checks SPF, DKIM, and DMARC to verify proper configuration status. The SPF and DMARC record generators facilitate the creation and configuration of these two email authentication mechanisms to enhance email verification while preventing SMTP errors.
